one wire Alternator and voltage regulator question

A parallel path helps, because it relieves pressure on the original, the bulkhead. 30A may not be enough tho

IF EG you create a short parallel charging path direct to the battery, this drops the original problem by more than half, even if you only use the same size wire. This is because battery charging current is now greatly reduced through and back out of the bulkhead, and that current is mostly "INTO" the car for headlights, etc. The fact that the new path is shorter and does not have lossey terminals/ connectors means a much lower resistance path